David, Here's my editorial comment: Assuming the investigation was done in a matter of days, I would not say 'insufficient rinsing' was the root cause. Louis Hart -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David Bealer Sent: Wednesday, November 11, 2015 12:14 PM To: [log in to unmask] Subject: Re: [TN] Unusual solder mask defect... I have seen a similar situation, the board house investigated the defect and reported back that the root cause was insufficient rinsing so some LPI mask was left in the holes after the solder mask was imaged and developed before it was baked to complete the cure. David Bealer SMT Department Manager office 800-637-2645 x6022 cell 217-474-8760 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of James Head Sent: Wednesday, November 11, 2015 10:51 AM To: [log in to unmask] Subject: Re: [TN] Unusual solder mask defect... Just one idea, with a negative film, the fab-houses phototooling/developing process for their artwork when they created the artworks for this design wasn't up to scratch and they have a "grey-scale" spot rather than a "black" spot for the offending pad/hole which is letting some light through. James James Head BEng CID+ MIIE MIET Senior PCB CAD Engineer Crowcon Detection Instruments Limited 172 Brook Drive Milton Park OX14 4SD Telephone: +44 (1235) 557700 ext. 7885 E-mail: [log in to unmask] ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________